When you first make the task, click the drop-down menu that says "Repeat" (on the right hand side) and check how often you want it to repeat. If you click the magic wand you can enter a phrase according to certain parameters. You can also check "Repeat from" Completion or Due date - ie, the date you actually complete the task, or the date you set as the due date.

It also has some interesting syntax-based features...you can hide a task that's scheduled in the future by using > (meaning "don't display until this date") in front of the date, or an = sign which means the task can only be completed on that date. At the bottom of the page there's a link to show the tasks being hidden by these filters. There may be others as well that I haven't yet learned. The > is very helpful and I'm using it a lot to keep my list uncluttered by things that don't yet apply, but I don't want to forget about.